The use of re-closable flexible pouches has seen dramatic increase in the last few years. Heretofore the primary market for bags with slider zippers has been a consumer who purchases empty slider bags and then fills the slider bags with products at home. However, with the increasing popularity of slider bags most manufacturers now tend to package their food and non-food products in slider bags for sale to consumers. The slider bags are a great convenience to the consumer who purchases these product filled bags especially for products of the type where only a portion of the product is used at any given time. The product applications for which slider bags may be used are virtually unlimited.
Plastic bags having zipper closures typically consist of two substantially similar sized sheets of plastic film (usually supplied from a pair of continuous web spools or rolls) which are then sealed together at a lower end of the sheets to form a front layer and a rear layer, with the seal forming a bottom edge of the bag. Alternatively, the plastic bag may be formed by a length of bag film folded upon itself to form a front layer and a rear layer connected by an integral bottom edge defined by the fold. Side edges of the plastic bag are typically sealed using a sealing head. The zipper typically has a two opposing walls with pairs of inter locking members on each side. When the two walls of the zipper are brought together the interlocking members lock and provide a seal to the bag.
The slider device typically includes a separator or plow-type structure in the middle, or at one end, that opens a zipper closure mechanism having male and female interlocking profiled elements or closure profiles when the slider device travels in a first direction along the zipper closure. The sidewalls of the slider device are inwardly tapered from one end to the opposite end so that the sidewalls engage the closure profiles and progressively move them into engagement to close the re-closable package when the slider device is moved along the zipper closure in a direction opposite to the first direction.
The typical slider bags that are being manufactured are airtight as far as solids and powders are concerned. However, the bags currently available are not leak proof. The bags are also not child proof.
The problem of leakage is two fold in that leakage occurs due to the improper sealing of the side edges and also due to improper design of the slider and zipper.
The zipper closure itself is airtight along its length due to the releasable and reusable seal formed by the inter-locked profile. Re-closable packages that include a slider device to more easily open and close the profiles typically face problems in providing a liquid tight seal across the entire length of the zipper closure due to the fact that the slider includes a plow device used to separate the closure profiles as the slider is moved along the length of the zipper closure. Thus a portion of the zipper closure beneath the plow remains open at all times.
Another drawback of existing bags is that they offer no resistance to opening by young children. Prescription drugs, medicines, important documents and a variety of other products need to be kept out of the reach of children. Sliding the slider in the opening direction easily opens re-closable bags with slider zipper presently available.
Co-pending application 1974/DEL/04 overcomes the problem of leakage and provides for a novel slider for a re-closable bag that eliminates the gaps in the zipper at the closing end and the same is incorporated here in entirety. The application provides for a slider that has bottom protrusions at both ends of the slider such that irrespective of the direction of movement of the slider the lower pair of interlocking members of the zipper are sealed. The slider also provides for a separating means or plow that does not extend beyond the upper pair of interlocking members. The separating means is also slanted such that at the end sealing position of the slider the separating means provides an effective seal.
U.S. Pat. No. 6,220,754 provides for one such closure device where the separator finger extends into the closure elements without extending completely through the closure elements. The portion of the closure elements below the separator finger is occluded when the slider is at the first end of the fastening strip. The document however relies on forces acting on the two walls of the zipper due to the position of the slider and the position of the two walls before and after the slider location for this end occlusion. No satisfactory solution is provided to the drawback of the separating means keeping the upper pair of interlocking members open at the end position.
U.S. Pat. No. 5,836,056 also relates to a slider zipper assembly that aims at eliminating the escape gaps at the edges of the zipper when the slider is in the closing position. The slider also has a separating plow that depends from the top surface and is preferably placed at the opening edge of the slider. The separating means penetrates the top pair of interlocking elements but not the bottom pair of inter-locking elements. However, the drawback of the separating plow at the closing end remains.
There is a strong requirement for a re-closable bag that is leak proof and child proof. The invention provides for such a bag.